Implantable prosthetic devices have been used in numerous locations in the body. The most common use has been for restoring or improving upon normal body contour or augmenting as well as reconstructing the female breast. The most common breast prosthesis is similar to that disclosed in U.S. Pat. No. 3,293,663 to Cronin, in which there is a flexible elastomeric container, typically silicone, which is filled with a soft gel, typically silicone gel or a saline solution or a combination of both.
It is known that when a prosthetic device, including the Cronin type device, is implanted in the body, fibrous scar tissue encapsulates the device. This encapsulation leads to a problem of spherical scar contracture. As the scar tissue surrounds the prosthetic device it tends to contract, thereby causing the gel filled sac to assume a minimum volume configuration or spherical configuration. The problem of spherical scar contracture causes the breast implant to change from a shape approximating that of a natural human breast to that of a tennis ball.
Numerous solutions to the spherical scar contracture problem have been proposed. Friesch U.S. Pat. No. 4,205,401 proposes the use of a relatively rigid restraining means which is contained within the fluid filled sac to thereby reduce the tendency of the tissue to distort the prosthesis into a sphere. Hamas U.S. Pat. No. 4,264,990 discloses the use of a prosthesis which contains a flexible backing material containing at least one internal passageway or compartment into which a rigidifying material may be forced or emplaced. In this way the backing becomes inflexible in an attempt to prevent spherical encapsulation of the implant. Hamas U.S. Pat. No. 4,531,244 discloses a prosthesis containing an outer envelope composed of a plurality of firm protruberances distributed substantially equally thereover. As scar contracture occurs, the relatively rigid protruberances are forced toward the gel filled sac, press on the gel filled sac, the gel flowing under pressure into the space between the protruberances.
The amount of spherical scar contracture which develops varies from patient to patient, and sometimes even differently respecting two implants in a single patient. The length of time which spherical scar contracture takes to develop also varies from patient to patient. Knowledge as to the etiologic factors behind spherical scar contracture is still developing. Some contributing factors are believed to be the tendency of the human body to wall off foreign substances, the formation of blood clot, infection, the presence of small operating field contaminants such as talcum powder, silicone gel bleed through elastomer membrane and chronic irritation due to movement of the implant at the interface between the body tissues and implanted materials.
Other problems with breast implants include postimplantation asymmetry, breast ptosis and implant rupture. These problems, along with spherical scar contracture, can lead to patient discomfort, unacceptable deformation and shape of the breast and implant, loss of breast volume, gel dissemination and migration to distant points within the body, bleeding after surgical lysis of spherical contractures and even life-threatening systemic infection. In severe cases it is necessary to reoperate to remove or replace the prosthesis and to incise or excise the scar capsule or to remove blood clots which may result from closed lysis ("closed capsulotomy") of the contractures. The risks of reoperating include the risks of anesthesia, infection, additional scarring, other morbidity, and economic costs. When the results of the reconstructive or augmentative implantation are less than anticipated a loss of self esteem in the patient results.
Brauman U.S. Pat. No. 4,648,880 discloses the use of a flexible container with a soft gel or fluid filling and an outer plastic or polymeric covering bonded to the flexible container and substantially encompassing the container. The outer covering is preferably made from Dacron or Teflon and has numerous pores or interstices as well as a rough textured external surface. The covering is believed to disperse or disorganize the forces of encapsulating scar tissue sufficient to avoid formation of a spherical capsular contracture. Brauman finds that the use of knitted polyester fiber such as Dacron, is found to be superior because it provides more elasticity and tissue ingrowth.
While it is believed that dispersion or disorganization of the scar tissue is beneficial in reducing spherical capsular contraction, it has proved extremely difficult to construct useful coverings out of Teflon. While Teflon is an exceptionally good biocompatible material, it has proved difficult to utilize as a covering material due to the difficulty of attachment to an enclosed elastomeric sac.
Other attempts have been made to limit spherical scar contracture, implant/breast deformation, or to deal with it once it has occurred. Approaches utilized previously include: (1) a normal saline barrier contained within its own silicone elastomer shell placed between the elastomer-encased gel portion of the implant and the body tissue, (2) overfilling the prosthesis at the time of implantation and subsequently bleeding off excess fluid to allow for a softer implant, (3) underfilling the implant at the time of implantation and subsequently adding fluid to counteract the forces of scar contracture with perhaps later bleed off, (4) using steroids, either injected into the tissue surrounding the implant or into the interior of the implant or administered perorally in the post-operative period, (5) closed lysis of the contracture by applying pressure external to the breast sufficient to tear the scar capsule, (6) open lysis of the scar contracture through a second larger incision and more aggressive and extensive surgery to remove or weaken the scar capsule, (7) removal of the submammary implant and placing a different implant either into the submammary plane or submuscularly, (8) massage of the breast and applying external pressure in order to keep the capsule soft and pliable, and (9) massage of the breast in a circular fashion to maintain an oversized "pocket" significantly larger than the implant.